Ford Global Technolgoies, LLC

Ford Motor Company Limited

Yi-Hsin Pao

Vivek Amir Jairazbhoy

Richard Keith McMillan

Xu Song

Xingyi Xu

Venkateswara Anand Sankaran

Jun Ming Hu

Dangrong Ronald Liu

Chan-Jiun Ed Jih

Wen-Je Jung

Chan-Jiun Jih

There is disclosed herein a surface mount printed circuit board having a substrate, at least one surface mount device, at least two mounting pads per device, solder joints connecting the terminations of the device to their respective mounting pads, at least one rectangular lifter pad on the substrate amid the mounting pads, and a solder mass on each lifter pad in contact with the bottom surface of the device. The inner and outer extensions of the mounting pads, the size, number, and shape of the lifter pads, and the amounts of solder deposited on the mounting and lifter pads are designed such that the solder joint has preferably convex outer fillets, the device is maintained at a predetermined height above the mounting pads, the inner fillet angle is maintained above a predetermined minimum angle to increase solder joint crack initiation time, and the overall solder joint crack propagation length is increased. An alternate embodiment also includes plugged vias under the lifter pads and/or mounting pads, with gas pockets trapped between the solder masses/solder joints and the plugged vias. This trapped gas pocket provides additional buoyant force upon the SMD during reflow.

Optimized solder joints and lifter pads for improving the solder joint

A method for joining a component to a substrate applies a base solder portion to the substrate and provides a standoff solder portion in the base solder portion. The standoff solder portion has a higher melting temperature than the base solder portion and a height which substantially corresponds to a desired standoff height between the component and the substrate. The component is positioned on the standoff solder portion and the base solder portion is melted under reflow conditions to form a solder joint between the component and the substrate. This joint substantially encapsulates the standoff solder portion, wherein the reflow conditions create a dendritic structure between the base solder portion and the standoff solder portion.

Standoff controlled interconnection

There is disclosed herein a leadless electronic component (LEC) which avoids solder joint crack initiation. A preferred embodiment of the LEC 110 comprises a body portion 112 having terminations 114 arranged thereabout, each termination having a bottom portion 124 with an interior edge 126, wherein the interior edge has a substantially meniscus-like shape oriented so as to be concave with respect to a centroid of the LEC.

Meniscus-shape terminations for leadless electronic components

A power module has a metallic base plate layer and a substrate layer that has a first metallic layer, a dielectric layer, and a second metallic layer. A solder layer thermally and electrically connects the second metallic layer to the base plate. A plurality of silicon dice are mounted to the first metallic layer of the substrate. The solder layer has a void development region which after a predetermined number of thermal cycles does not significantly increase. The silicon dice are oriented on the substrate layer so that the silicon dice are not aligned over the void development region corresponding to the useful life of the module. The metallic base plate may also be mounted to a heatsink through a thermal grease layer. The heatsink may comprise the outer covering of the power module.

Power module with silicon dice oriented for improved reliability

A novel printed circuit board is disclosed. The printed circuit board has a high density of circuit components with lower circuit components residing within recesses in a printed wiring board and upper circuit components residing above the lower circuit components.

Growing community of inventors

Livonia, MI, United States of America

Yi-Hsin Pao